1000-49-3Relevant articles and documents
Alkali Metal Hydrides: New Metallating Reagents at Silicon
Corriu, Robert J. P.,Guerin, Christian
, p. 168 - 169 (1980)
New procedures for the preparation of organo-silyl-sodium or potassium, which undergo coupling reactions with alkyl, allyl, and benzyl halides and α-enones, are reported.
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Freidlina,R.Kh. et al.
, (1961)
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Sakurai,Kondo
, p. C46 (1975)
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Blake,D. et al.
, p. 618 - 622 (1961)
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Synthesis of Trimethylsilyloxy and Hydroxy Compounds from Carbanions and Bis(trimethylsilyl)peroxide.
Camici, Lucia,Dembech, Pasquale,Ricci, Alfredo,Seconi, Giancarlo,Taddei, Maurizio
, p. 4197 - 4206 (1988)
The reactions of bis(trimethylsilyl)peroxide with alkyl, vinyl, alkynyl, aromatic and heteroaromatic anions are described.Depending on the reaction conditions, the trimethylsilyloxy derivatives can be obtained alone or together with the corresponding trimethylsilyl derivatives, which is sometimes the major product.Enolates, generated using magnesium diisopropylamide give the corresponding hydroxycarbonyl compounds in good yields.An attempt to rationalise the above results is given, emphasising the wide use of bis(trimethylsilyl)peroxide in organic synthesis as an electrophilic hydroxylation reagent.
Transfer Hydrogenation of Alkenes Using Ethanol Catalyzed by a NCP Pincer Iridium Complex: Scope and Mechanism
Wang, Yulei,Huang, Zhidao,Leng, Xuebing,Zhu, Huping,Liu, Guixia,Huang, Zheng
, p. 4417 - 4429 (2018)
The first general catalytic approach to effecting transfer hydrogenation (TH) of unactivated alkenes using ethanol as the hydrogen source is described. A new NCP-type pincer iridium complex (BQ-NCOP)IrHCl containing a rigid benzoquinoline backbone has been developed for efficient, mild TH of unactivated C-C multiple bonds with ethanol, forming ethyl acetate as the sole byproduct. A wide variety of alkenes, including multisubstituted alkyl alkenes, aryl alkenes, and heteroatom-substituted alkenes, as well as O- or N-containing heteroarenes and internal alkynes, are suitable substrates. Importantly, the (BQ-NCOP)Ir/EtOH system exhibits high chemoselectivity for alkene hydrogenation in the presence of reactive functional groups, such as ketones and carboxylic acids. Furthermore, the reaction with C2D5OD provides a convenient route to deuterium-labeled compounds. Detailed kinetic and mechanistic studies have revealed that monosubstituted alkenes (e.g., 1-octene, styrene) and multisubstituted alkenes (e.g., cyclooctene (COE)) exhibit fundamental mechanistic difference. The OH group of ethanol displays a normal kinetic isotope effect (KIE) in the reaction of styrene, but a substantial inverse KIE in the case of COE. The catalysis of styrene or 1-octene with relatively strong binding affinity to the Ir(I) center has (BQ-NCOP)IrI(alkene) adduct as an off-cycle catalyst resting state, and the rate law shows a positive order in EtOH, inverse first-order in styrene, and first-order in the catalyst. In contrast, the catalysis of COE has an off-cycle catalyst resting state of (BQ-NCOP)IrIII(H)[O(Et)···HO(Et)···HOEt] that features a six-membered iridacycle consisting of two hydrogen-bonds between one EtO ligand and two EtOH molecules, one of which is coordinated to the Ir(III) center. The rate law shows a negative order in EtOH, zeroth-order in COE, and first-order in the catalyst. The observed inverse KIE corresponds to an inverse equilibrium isotope effect for the pre-equilibrium formation of (BQ-NCOP)IrIII(H)(OEt) from the catalyst resting state via ethanol dissociation. Regardless of the substrate, ethanol dehydrogenation is the slow segment of the catalytic cycle, while alkene hydrogenation occurs readily following the rate-determining step, that is, β-hydride elimination of (BQ-NCOP)Ir(H)(OEt) to form (BQ-NCOP)Ir(H)2 and acetaldehyde. The latter is effectively converted to innocent ethyl acetate under the catalytic conditions, thus avoiding the catalyst poisoning via iridium-mediated decarbonylation of acetaldehyde.
Reactions at interfaces: Oxygenation of n-butyl ligands anchored on silica surfaces with methyl(trifluoromethyl)dioxirane
Mello, Rossella,Martinez-Ferrer, Jaime,Alcalde-Aragones, Ana,Varea, Teresa,Acerete, Rafael,Gonzalez-Nunez, Maria Elena,Asensio, Gregorio
experimental part, p. 10129 - 10139 (2012/02/14)
The oxygenation of n-butyl and n-butoxy chains bonded to silica with methyl(trifluoromethyl)dioxirane (1) revealed the ability of the silica matrix to release electron density toward the reacting C2-H σ-bond through the Si-C1 and Si-O1 σ-bonds connecting the alkyl chain to the surface (silicon β-effect). The silica surface impedes neither the alkyl chain adopting the conformation required for the silicon β-effect nor dioxirane 1 approaching the reactive C2 methylene group. Reaction regioselectivity is insensitive to changes in the solvation of the reacting system, the location of organic ligands on the silica surface, and the H-bonding character of the silica surface. Reaction rates are faster for those organic ligands either within the silica pores or bonded to hydrophilic silica surfaces, which evidence the enhanced molecular dynamics of confined dioxirane 1 and the impact of surface phenomena on the reaction kinetics. The oxygenation of n-butyl and n-butoxy chains carrying trimethylsilyl, trimethoxysilyl, and tert-butyl groups with dioxirane 1 under homogeneous conditions confirms the electronic effects of the silyl substituents and the consequences of steric hindrance on the reaction rate and regioselectivity. Orthosilicic acid esters react preferentially at the methylene group adjacent to the oxygen atom in clear contrast with the reactivity of the carboxylic or sulfonic acid alkyl esters, which efficiently protect this position toward oxidation with 1 (Figure presented).
Alkylsilyl Cyanides as Silylating Agents
Mai, Khuong,Patil, Ghanshyam
, p. 3545 - 3548 (2007/10/02)
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